(1) Field of the Invention
The present invention belongs to the technical field of resolution conversion technology.
(2) Description of the Related Art
Resolution conversion technology refers to performing conversion processing on a video signal supplied from a recording medium or a broadcast wave to obtain a higher-resolution video signal, and outputting the video signal to a television, and this technology has gained a greater level of importance due to the widespread use of high-definition television sets in recent years.
For example, if an original video is SD video having 720 horizontal pixels and 420 vertical lines, performing resolution conversion on the original video enables obtaining HD video having 1920 horizontal pixels and 1080 vertical lines. Technology for converting an original video signal into a higher-definition video signal in this way is called “up-conversion”. The opposite is called “down-conversion”. The invention described in the following patent document is known as a conventional technology for resolution conversion.
The conventional technology described in patent document 1 performs resolution conversion on a video signal having 480 vertical lines (525 scanning lines) in conformity with a standard television signal.
Furthermore, many resolution conversion techniques have been proposed, such as resolution conversion using a statistical technique to increase resolution (see non-patent document 1) and resolution conversion on a video signal having a plurality of frames (see non-patent document 2).    Patent document 1: Japanese Patent Application Publication No. 02-189086 (FIG. 1)    Non-patent document 1: Research on Making an Image High Definition Using a Statistical Technique (Information Technology Research Institute of Nagano Prefecture, Research Report No. 18)    Non-patent document 2: Making an Image High Definition Using a Multi-frame Method (Information Technology Research Institute of Nagano Prefecture, Research Report No. 19)